if a postsynaptic cell recieves only a single synaptic input what is the only way voltages can sum together

well schools are being forced to embrace computers. unlike their "digital immigrant" teachers, these students are "digital natives", born into a world where technology is an integral part of everyday life. almost every student has access to a multitude of computers, laptops and tablet devices. it would be crazy to assume an assignment would  not be written on computer in this day and age.

don't delete this trying to

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.