Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Generally, 3d transition metals have high melting points. Reason R: Involvement of 3d-electrons in addition to 3s-electrons in the interatomic metallic bonding. In light of the above statements, choose the most appropriate answer from the options given below:

In frogs, the number of pairs of cranial nerves arising from the brain are

Three identical p-n junction diodes $D_{1}$, $D_{2}$ and $D_{3}$ are connected across a battery as shown in the figure. If the width of the depletion regions of $D_{1},$ $D_{2}$ and $D_{3}$ are $W_{1},$ $W_{2}$ and $W_{3}$, respectively, then the correct option is: [Image Placeholder]

Which of the following statements regarding photorespiration are correct? (a) Do not occur in $C_{3}$ plants (b) $CO_{2}$ is consumed and $O_{2}$ is generated (c) Phosphoglycolate is formed (d) No synthesis of ATP and NADPH. Choose the correct answer from the options given below:

A ray of light with wavelength $\lambda$ is incident on three different photoelectric cells namely 1, 2 and 3. The threshold wavelength of these photoelectric cells are $\lambda_{1}$, $\lambda_{2},$ and $\lambda_{3,}$ respectively and the magnitude of stopping potentials of these cells are $V_{1}$, $V_{2}$ and $V_{3},$ respectively. The relation between $\lambda$ and threshold wavelengths are $\lambda_{1}\lambda$ and $\lambda_{3}>>\lambda$. The correct option is: