Hi, I have a question for which the answer is provided but I don't know how it is derived, could you help to explain it step by step please?

for this question I basically had to choose one of the following options, first either (constant/increasing/decreasing) and then (would/would not have). It is a "fill in the blank" kind of a question. The answer is 1.Correct 2. Would but I don't understand why.

Thank you in advance for all your help.

If the exponents in the production function were [LEG for s1 and [LEG for 2, this production function would exhibit {constant1 increasingf decreasing} returns to scale and {would would not] have diminishing technical rate of substitution. constant, would not increasing. would decreasing. would not decreasing. would ; constant, would