Easy
remember
(x^m)(x^n)=x^(m+n)
basically add exponens when the base is same
(13^-11)(13^16)(13^-3)(13^4)(13^-5)=
13^(-11+16-3+4-5)=
13^(5-4)=
13^1=13
It is D because every time there is a box in the corner it's a right angle and they are always 90°
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