The correct answer is option 2: Both the statements are individually true but Statement II is not the correct explanation of Statement I.

Statement I states that at high temperatures, hydrogen can reduce PbO to elemental lead. This statement is true because hydrogen gas can act as a reducing agent, meaning it can donate electrons to another substance to reduce its oxidation state. In the case of PbO, hydrogen can react with the oxygen in PbO to form water vapor, resulting in the reduction of PbO to elemental lead.

Statement II states that hydrogen has great affinity to oxygen. This statement is also true because hydrogen and oxygen can readily react to form water (H2O). However, this statement does not directly explain or provide a reason for Statement I. While it is true that hydrogen has an affinity for oxygen, it does not necessarily imply that hydrogen can reduce PbO to elemental lead.

Therefore, both statements are true and independent of each other, and Statement II is not an explanation of Statement I.