To solve this problem, we need to identify the factors that favor the formation of oxyhaemoglobin in the alveoli. Let's analyze each option:$\newline \bullet$Option 1: Low $p$CO$_2$ and High $$H$^+$ concentration$\newline$ - Low $p$CO$_2$ is favorable for oxyhaemoglobin formation as it reduces the Bohr effect, which promotes oxygen binding.$\newline$ - However, high $$H$^+$ concentration (low pH) is not favorable as it promotes the release of oxygen from haemoglobin.$\newline$ - Therefore, this option is not correct.$\newline \bullet$Option 2: Low $p$CO$_2$ and High temperature$\newline$ - Low $p$CO$_2$ is favorable for oxyhaemoglobin formation.$\newline$ - High temperature is not favorable as it decreases haemoglobin's affinity for oxygen, promoting oxygen release.$\newline$ - Therefore, this option is not correct.$\newline \bullet$Option 3: High $p$O$_2$ and High $p$CO$_2 \newline$ - High $p$O$_2$ is favorable for oxyhaemoglobin formation as it increases the partial pressure gradient for oxygen binding.$\newline$ - High $p$CO$_2$ is not favorable as it enhances the Bohr effect, promoting oxygen release.$\newline$ - Therefore, this option is not correct.$\newline \bullet$Option 4: High $p$O$_2$ and Lesser $$H$^+$ concentration$\newline$ - High $p$O$_2$ is favorable for oxyhaemoglobin formation.$\newline$ - Lesser $$H$^+$ concentration (higher pH) is favorable as it reduces the Bohr effect, promoting oxygen binding.$\newline$ - Therefore, this option is correct.$\newline$Thus, the most appropriate answer is Option 4: High $p$O$_2$ and Lesser $$H$^+$ concentration.