Johann Mendel is considered a genius much ahead of his time, as he proposed the concept of "factors" (now called genes) based on the fact that . . . . . . .

$A$ test cross is defined as:

Define/Explain: $F_2$ generation.

Mendel's work remained unrecognized for a long time due to:
$I.$ Communication was not easy.
$II.$ The concept of factors which did not blend was not accepted.
$III.$ The use of mathematics to explain biological problems was unacceptable.
$IV.$ He could not provide any physical proof for the existence of factors.
Choose the right combination.

Mendel published his work on the inheritance of characters in $1865$,but it remained unrecognized until $1900$ because:
$(a)$ He could not provide any physical proof for the existence of factors.
$(b)$ His concept of factors as stable,discrete units that controlled the expression of traits did not find acceptance from his contemporaries.
$(c)$ Mendel's approach of using mathematics to explain biological phenomena was considered ahead of its time and unconventional.
$(d)$ Communication was not easy (as it is now),and his work could not be widely publicized.

In Mendel's experiments,the nature of seed coat,flower colour,position of flower,pod colour,stem height,etc.,are referred to as: