With the morality strata, it's calculated afrom how high, or low, U5MR and adult male mortality is. But how do you know when something is low, very low or high?
While I believe it is difficult to distinguish between what the difference between for example, 'low' and 'very low' or 'high' and 'very high' adult mortality rate would be, there's nothing to worry about since data can be interpreted differently (to a certain extent..) and examiners do take that into account... hopefully. Usually, if the mortality strata is 250 per 1000 people (would be males aged 15-59 since it's for the mortality strata), I could consider that as high, but you could say that's very high. Hence, my answer would be strata D, and yours would be strata E. I believe I have seen a VCAA exam question asking about mortality strata based on data and both answers D and E were accepted where the mortality rate was 'high-ish'.
But still, here is a rough guide to (hopefully) help you: If you're given a table with data for adult mortality and U5MR, then you have to make your classification based on whether:
The adult mortality rate is very low, low, high, or very high and whether the U5MR is very low, low, or high.
To make this classification I'll give you some estimated numerical values..
For very low - If the data is per 1000 population (for adult mortality) or per 1000 live births (for U5MR), then examples would be countries like Australia or Japan which would have a U5MR of 3 or 5 per 1000 live births. (These figures are very small so that gives it away, but also when you'll be given data you will be provided with the country too, this should also give you an idea of what strata it belongs to)
For low - I feel as though the distinction between low and very low is hard to make, but it would be relatively higher than low.. for example Indonesia may have a mortality rate of 43 per 1000 population - which isn't exactly very low, but it's still comparatively lower than a country which has for e.g. has an U5MR of 139 per 1000 live births.
For high - I would consider 65-140 per 1000 live births high.
For very high - 140+ per 1000 live births, my reasoning for this: VCAA Examiner's report 2012. In a 2012 question where Afghanistan which was presented as having an U5MR of 199 per 1000 live births, the examiner's report stated that this is 'very high'.
Generally speaking, as long as you are able to identify that a mortality rate of 5 per 1000 population is very low, and in comparison that 209 per 1000 population is very high, you should be fine. Anyways.. I hope I was able to help, but I'd like to stress that this is based on 40% of my own understanding + 60% of what my teacher has told me and what the examiner's report has shown, so I'm sorry if it's not 100% accurate.