7670
The combinations of the endothelin - 1 receptor antagonists bosentan or ambrisentan with the phosphodiesterase 5 inhibitors sildenafil or tadalafil are current standard therapies of advanced pulmonary arterial hypertension .
 Chemical: bosentan; Chemical: ambrisentan; Chemical: sildenafil; Chemical: tadalafil
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: bosentan, ambrisentan, sildenafil, tadalafil 
Answer:
 Chemical: bosentan; Chemical: ambrisentan; Chemical: sildenafil; Chemical: tadalafil